In recent years, in order to analyze a trace amount of a substance such as proteins or nucleic acids (DNA, for example) with high accuracy and high performance, a microanalysis system has been used in the field of science, such as biological chemistry or analytical chemistry, or in the field of medicine.
A system for performing electrophoresis using a microchannel chip having a fine channel has been known as an example of a microanalysis system. A microchannel chip in which an electrode is disposed so as to be exposed to a through-hole or a groove has been known as the microchannel chip in the system (see PTLs 1 and 2, for example). In the microchannel chip, a film formed with a conductive layer, which functions as an electrode, on a surface thereof is brought to be adhered to a first surface of a base having the through-hole for accommodating fluid, the groove functioning as a channel for the fluid and the like.
The microchannel chip disclosed in PTL 1 is shown in FIG. 1. Microchannel chip 10 has a pair of through-holes 26 penetrating base 18, groove 14 which is formed on a first surface of base 18 and causes the pair of through-holes 26 to communicate with each other, film 20 which is brought to be adhered to the first surface of base 18 and covers openings of through-hole 26 and groove 14, electrode 28 which is formed on film 20, is exposed to through-hole 26 and extends at least to a peripheral edge of film 20, as shown in FIG. 1. By bringing film 20 to be adhered to base 18, through-hole 26 functions as a fluid container, and groove 14 functions as a channel. A liquid sample is supplied to through-hole 26 from an upper surface side of base 18. In addition, film 20 has an edge protruding further outside than an edge of base 18. External electrodes are respectively in contact with electrodes 28 and 28 on the edge of film 20 from above, and thereby voltage is applied to electrodes 28 and 28.